The invention relates to a method for producing a cup from a flat segment and a pot-like base, and also to an apparatus for producing a cup of this kind.
The aim of the invention is to improve a method and an apparatus for producing a cup.
According to the invention, a method for producing a cup from a flat segment and a pot-like base involves winding the flat segment onto a winding mandrel, so that there is an overlap in the region of the side edges of the segment, connecting the sections, which adjoin the side edges, in the region of the overlap, so that a conical sleeve is produced, inserting the pot-like base into the conical sleeve, and connecting a circumferential wall of the pot-like base in a substantially liquid-tight manner to an inner face of the sleeve.
The method according to the invention is intended for paper material and materials which can be processed in a similar manner to paper. By way of example, flat segments can comprise paper, paperboard or cardboard, and these flat segments can then firstly be wound in order to form a conical sleeve and secondly can be deformed in order to form a pot-like base. The paper material is expediently coated in a liquid-tight manner. In the same way or at least in a similar way to paper material, flat plastic materials are also processed to form cups. Flat plastic materials include, for example, plastic laminates. In this case, the flat plastic material which is present in segment form is likewise wound around a winding mandrel and connected in the region of the overlap in order to form a conical sleeve. A pot-like base can also be formed from the flat plastic material by a circular blank being folded approximately vertically upward in relation to a base area in its border region. The problems which occur with plastic materials which can be processed in a similar manner to paper are substantially the same as occur when processing paper material. The present invention can be used for plastic materials which can be processed in a similar manner to paper, but it is not specially designed for plastic materials which can be processed in a similar manner to paper, but rather can also be used for paper materials with considerable advantages, especially when the paper material comprises, for example, a very stiff and/or thick paperboard.
In one development of the invention, a pressing force is exerted in the region of the overlap when the sections which adjoin the side edges are connected, wherein the pressing force is greater in those regions which directly adjoin the bottom edge of the sleeve and the top edge of the sleeve than in the other regions of the overlap.
Therefore, according to the invention, provision is made to compress the paper material or material which can be processed in a similar manner to paper to a greater extent in the region of the bottom edge and of the top edge of the sleeve than in the centre region. As a result, specifically in the case of comparatively thick materials, the subsequent shaping of the bottom edge and of the top edge of the sleeve to form a top curl or a bottom skirt is considerably simplified.
In one development of the invention, the length of the region which directly adjoins the bottom edge of the conical sleeve is selected to be of such a size that the region extends at least over the outer face and inner face of a bottom skirt on the finished cup, the base and the sleeve being connected in a substantially liquid-tight manner to the said bottom skirt.
In order to produce a bottom skirt, the sleeve is generally folded over inwards through 180° and the wall of the pot-like base is accommodated in this folded-over portion. In order to be connected in a liquid-tight manner, the sleeve and the base are then pressed and/or connected in a cohesive manner in the region of the bottom skirt. Production of the bottom skirt is considerably simplified when the region of the overlap at the bottom edge of the sleeve is pressed to a greater extent than in the centre region, and therefore the overlap in the region of the future bottom skirt is flatter than in the centre region.
In one development of the invention, the length of that region which directly adjoins the top edge of the conical sleeve is selected to be of such a size that the region extends at least over the top curl on the finished cup.
In the region of the top curl, the overlap which is pressed flat to a greater extent than the centre region considerably simplifies production of the top curl. It goes without saying that the entire region of the overlap per se could be pressed together to a great extent. However, the pressing forces required for this purpose are so high that they would require considerable reinforcement of the apparatus or machine used for producing cups from paper material and materials which can be processed in a similar manner to paper. Owing to the overlap being pressed to a relatively great extent only in the region of the top edge and bottom edge of the sleeve, it is consequently also possible to process very thick paper materials or plastic materials which can be processed in a similar manner to paper without problems and without requiring major changes to the machine itself.
In one development of the invention, the flat segment is wound onto a winding mandrel in order to produce the conical sleeve, the cross section of the said winding mandrel differing from a circular shape and being either oval, elliptical or flattened in the region of the overlap of the segment edges.
In the case of very stiff paper materials or plastic materials which can be processed in a similar manner to paper, the use of a winding mandrel with a circular cross section results in deformation of the sleeve into a cross-sectional shape which differs from the circular shape after the sleeve is removed from the winding mandrel. This is caused by the double material layer in the region of the overlap. Even when the region of the overlap is sealed by a temperature effect, the circular shape is not maintained after the said sleeve is slipped off from the winding mandrel. Surprisingly, a winding mandrel with a non-circular cross section can provide help in this case. By way of example, the winding mandrel can be of oval or elliptical design, wherein the region of the overlap is then arranged on a planar section of the winding mandrel or a section of the winding mandrel with a relatively large radius of curvature. As an alternative, the winding mandrel can differ from the circular shape only in the region of the overlap and be flattened in the region of the overlap. In this case, the sleeve assumes a form with a circular cross section after being slipped off from the winding mandrel, even in the case of very stiff paper material and very stiff plastic material which can be processed in a similar manner to paper.
In one development of the invention, a pressing die is used in order to exert the pressing force, the said pressing die being at a further distance from the winding mandrel in the centre region than in its two end regions.
The pressing force which is relatively high in the region of the bottom edge and the top edge of the sleeve can be implemented in a simple manner using a pressing die of this kind.
In one development of the invention, a lower border of the sleeve, which lower border projects beyond the lower edge of the circumferential wall of the base, is folded over by means of a plurality of jaws, which can be displaced in the radial direction, inwards until the lower border assumes a predefined first angular position in relation to the centre longitudinal axis of the sleeve.
Even very stiff paper material or very stiff flat plastic material can be folded over in a very precise and reliable manner at the lower border of the sleeve by the said measures. In contrast to conventional methods for cup production in which the lower border of the sleeve is folded over by positioning a die parallel to the centre longitudinal axis of the sleeve, the radially displaceable jaws which are provided according to the invention reliably prevent the lower border of the sleeve from buckling during the folding-over process. Folding over the lower border, which forms a substep of the production of the lower, circumferential bottom skirt for connecting the sleeve and the base, can therefore be performed with very short cycle times and with process reliability.
In one development of the invention, proceeding from the first angular position of the lower border, the sleeve is folded over to a second predefined angular position by means of a die which can be moved parallel to the centre longitudinal axis of the sleeve.
After the lower border is moved by the jaws, which can be displaced radially inwards, to the predefined first angular position in which the lower border assumes, for example, an angle of between 50° and 60° in relation to the centre longitudinal axis, there is no longer any risk of buckling during further folding over of the border, and the border can be further folded over, for example into a second angular position in which the border assumes an angle of approximately 180° in relation to the centre longitudinal axis, in a proven manner by means of a die which can be positioned parallel to the centre longitudinal axis.
In the case of the invention, a first channel-like recess is made in the flat segment or in the conical sleeve, wherein the first channel-like recess runs at a constant distance from a relatively short bottom edge of the segment or a bottom edge of the sleeve, and the sleeve is folded over around the first channel-like recess in order to form a bottom skirt with the circumferential wall of the pot-like base, so that a region around the first channel-like recess forms a standing area for the cup when the sleeve is in the fully folded-over state.
Pre-embossing the region in which the bottom skirt will be formed in future is highly advantageous specifically in the case of very thick, and as a result stiff, paper material. The material can be pre-embossed either on the flat segment or only on the finished sleeve in this case.
In the case of the invention, a plurality of second, channel-like recesses which are situated next to one another and which extend from the first channel-like recess as far as the bottom edge of the segment or the bottom edge of the sleeve are embossed.
In one development of the invention, the material of the sleeve in the region of the top edge of the sleeve is heated, and the top curl is then formed.
In this way, forming of the top curl can be simplified specifically in the case of very stiff paper material or plastic material which can be processed in a similar manner to paper. Surprisingly, heating of the material before forming the top curl is helpful even in the case of paper material. It goes without saying that care must be taken to ensure that the paper material does not catch fire in the process.
In one development of the invention, lubricant is applied in the region of the top edge of the sleeve, and the top curl is then formed.
The problem on which the invention is based is also solved by an apparatus for producing a cup using a winding mandrel which tapers on one side, in which winding mandrel a cross section of the winding mandrel differs from a circular shape and is either oval, elliptical or flattened in the region of the overlap of the segment edges.
Surprisingly, a circular sleeve can be produced by a winding mandrel of this kind which differs from a circular shape in the case of very stiff paper material or very stiff plastic material which can be processed in a similar manner to paper. Owing to the overlap during the production of the sleeve, the sleeve is considerably stiffer in the region of the overlap since the material thickness is doubled there. Owing to an oval winding mandrel or a winding mandrel which is flattened in the region of the overlap of the segment edges, the sleeve, when it is removed from the winding mandrel, deforms in such a way that it acquires a circular shape in cross section.
In one development of the invention, a winding mandrel and a pressing die are provided in the apparatus for producing a cup, wherein the pressing die extends along a surface line of the winding mandrel, and wherein the pressing die is at a further distance from the winding mandrel in its central region than in its two end regions in a state in which it is mounted onto the winding mandrel.
The region of the overlap at the bottom edge and top edge of the sleeve can be pressed to a greater extent in a simple manner by a pressing die of this kind, as a result of which the wall thickness of the sleeve is reduced at the overlap in the region of the top edge and bottom edge of the sleeve. This considerably simplifies the subsequent forming of a top curl at the top edge of the sleeve and, respectively, of a bottom skirt at the bottom edge of the sleeve.